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<p>The best book I have seen on the subject of mechanisms is <a href="http://www.amazon.co.uk/Mechanisms-Mechanical-Sourcebook-Nicholas-Chironis/dp/0071361693/" rel="nofollow noreferrer">Mechanisms And Mechanical Devices by Neil Sclater and Nicholas P. Chironis</a>.</p>
<p><img src="https://i.stack.imgur.com/0WZ63.jpg... | 641 | 2012-12-07T16:29:15.963 | |design|mechanism| | <p>I am working with students (9th & 10th grade) on robotics and wanted to get a good book which covers basic mechanisms. Does anyone have any recommendations. Searching Google or Amazon yields many results, however, I thought the community might have a standard book to use. </p>
| Good book on mechanisms |
<p>There is a project on Google Code called <a href="http://code.google.com/p/mma7361-library/" rel="nofollow">MMA7361-library</a>. The <a href="http://www.geeetech.com/wiki/index.php/MMA7361_Triple_Axis_Accelerometer_Breakout" rel="nofollow">GE Tech Wiki</a> has a simple example showing how to use this library. Copied... | 642 | 2012-12-08T05:06:56.877 | |arduino|sensors|accelerometer| | <p>I recently purchased a 3-axis accelerometer from Amazon, and can't seem to find how it works. I've been looking for quite a while now, and haven't found any real clues. The x, y, and z values always seem to return the same values. They change when I tilt or move the accelerometer, but revert to about 120 for each re... | MMA7361 Accelerometer Always Displays Same Values |
<p>It is possibly a bias in the accelerometer. The measured non-zero results (like yours) are the bias. No idea if the magnitude of these biases is right, i.e., you may be experiencing more error than you should expect from a bias. To be clear, you can subtract this bias from your estimate of acceleration. However, yo... | 646 | 2012-12-10T11:51:14.537 | |design|electronics|accelerometer|calibration| | <p>I am trying to calibrate a MEMS accelerometer. I was able to calibrate it for the current axis which is parallel to gravity and shows correctly, 1g. But the other two axes which should be 0.00g are showing +-0.02g instead.
So, e.g., when the accelerometer's x axis is parallel to gravity, it should show (1g, 0g, 0g)... | MEMS accelerometer calibration |
<p>I'm in agreement with <a href="https://robotics.stackexchange.com/a/652/37">@movrev</a> but wanted to expand beyond the scope of a comment. RN-42 is slick. I'm coding for it now, and I think it is an excellent BT choice.</p>
<p>Low cost and multiple receivers (switches) appear to be mutually exclusive. You might... | 650 | 2012-12-10T17:44:15.900 | |sensors|circuit| | <p>I can control a relay from an Android smartphone using Arduino and Bluetooth as seen <a href="http://bellcode.wordpress.com/2012/01/02/android-and-arduino-bluetooth-communication/" rel="nofollow">here</a>.</p>
<p>However, it seems too costly to be using Arduino and a Bluetooth receiver for driving a switch. As long... | Can I make a simple Bluetooth receiver? |
<p>You can forcefully disable IR light for Kinect for Windows (by using the property <code>ForceInfraredEmitterOff</code>) which you cannot do for xbox Kinect. This feature is very useful when using multiple Kinect sensors because when their FOVs overlap, some serious issues arise.</p>
| 654 | 2012-12-11T09:58:33.730 | |sensors|kinect| | <p>As I see there is a huge price gap between the two \$223 vs \$99 (at amazon).</p>
<p>My intention is to use one of those from Ubuntu linux to perform depth sensing, navigation etc. and naturally I prefer the cheaper.
However I am not sure if I miss some important point while betting on the Kinect for Xbox version.... | What is the difference between Kinect for Windows and Kinect for XBox? |
<p>You could use a simplified Linux (without the X-Windowing and other graphics utilities that a robot may not need). Raspian-Lite is one such OS.</p>
<p>Then there are a number of robot frameworks that will run on the Raspberry Pi. They run under the Linux OS.</p>
<p>ROS (the Robot Operating System) is one of the mo... | 667 | 2012-12-12T19:57:51.837 | |raspberry-pi|operating-systems| | <p>Is there an operating system for the Raspberry Pi that is specifically made for running robotics applications? Or an operating system whose purpose is to optimized just to run a few specific programs?</p>
<p>I've been working with an Arduino for a while now. As far as efficiency goes, it makes sense to me to just u... | Raspberry Pi operating system for robotics |
<p>As NXC is a compiled language, I would assume calling a non-existent function or accessing a non-existent variable would throw a syntax error during compilation as it does in other compiled languages I have used.</p>
<p>Conversely, in interpreted languages like PHP and Python you can often call or access things tha... | 671 | 2012-12-13T04:43:47.557 | |nxt|programming-languages|mindstorms|not-exactly-c| | <p>Is there a way to check if a task, function or variable exists in Not eXactly C?</p>
<p>I know that in PHP you can use <code>isset()</code> to check if a variable exists and <code>function_exists()</code> to do the same for a function, but is there a way to do that in NXC?</p>
<p>I am specifically interested in ch... | Check if task exists in Not eXactly C |
<p>If I were you, I would first (1) read the <a href="http://www.onsemi.com/pub_link/Collateral/LM2576-D.PDF" rel="nofollow noreferrer">LM2576 datasheet</a>.
I'm assuming you are using a circuit similar to the schematic and PCB layout on page 23 of the LM2576 datasheet.
I'm guessing you've tweaked the circuit slightly,... | 684 | 2012-12-15T13:14:25.053 | |motor|electronics|power| | <p>I have an LM2576 circuit plus an adjuster to adjust the output voltage, for controlling motor speed in a line follower robot. The circuit works great when adjusted to give out low voltages, but when I adjust it to higher voltages for my motors to go faster, it works great for 1-2 minutes, then suddenly cuts down the... | Why does our LM2576 circuit suddenly cut down the power? |
<p>As a follow-up (albeit after 2.5 years) I would like to add some other things that I was able to work on and might possibly help you / anybody else foraying into this field.</p>
<p><strong>Option 1)</strong> Use an existing robot hardware and add your own sensors and actuators:</p>
<p>For e.g.: I had access to a i... | 687 | 2012-12-15T21:31:07.840 | |kinect| | <p>I want to learn robotics and really interested in making a robot based on Kinect sensor.</p>
<p>I see so many projects like <a href="http://www2.macleans.ca/2011/11/03/the-150-robot-revolution/" rel="nofollow">this one</a>, and just wondering how it works on top level. I downloaded Kinect SDK and did some basic tut... | Robotics with Kinect |
<p>I've seen a number of systems in this configuration and most went for an outside track solution. Part of the reason for this is control of bend radius. With an outside track, the bend is obvious at all positions and it is clear when you <em>run out of track</em>.</p>
<p>If you are bothered about cabling complexity,... | 689 | 2012-12-16T01:59:01.610 | |control|wiring|routing|motion| | <p>I'm building a motion control platform with 3 DoF: 1 axis of rotation (theta) and 2 cartesian (x,y). In most applications, like wrist actuation, you have an X-Y stage with a rotating servo as the stage's payload. This configuration works well since little of the power and data wiring needs to transit to the non-line... | Cable routing in theta, x, y motion control system. Better inside or outside? |
<p>When using the EKF (or standard KF) on a real robot, you will want to tell the filter how much noise there is in each measurement, and in the process.</p>
<p>The purpose of this is so that the Kalman filter can decide how much it "trusts" each source of data, and therefore, the weighting to give each measurement in... | 690 | 2012-12-16T05:29:07.907 | |slam|kalman-filter| | <p>When using an EKF for SLAM, I often see the motion and measurement models being described as having some noise term. </p>
<p>This makes sense to me if you're doing a simulation, where you need to add noise to a simulated measurement to make it stochastic. But what about when using real robot data? Is the noise a... | Noise in motion and measurement models |
<p>Yes, there is a difference between the Create and an off-the-shelf Roomba. The Create doesn't have a vacuum motor or any of the cleaning brushes. And there is an empty payload bay where all of the cleaning stuff used to be. Additionally, the Create has an added microcontroller on it that you can push code onto. ... | 693 | 2012-12-18T01:47:33.573 | |ros|roomba|irobot-create| | <p>Is there anything different between a iRobot Roomba and the Create? I want go start building my own turtlebot and playing with ROS but with the cost of all the parts I'm going to have to do it piece by piece. It's pretty easy to find cheap used Roombas. </p>
| Can I use ROS with a Roomba? |
<p>They aren't. The word servo refers solely to a device that uses negative feedback for control.</p>
<p>Gearboxes or cheap brushed motors can be noisy. You can get very quiet systems if you are willing to pay for it.</p>
<p>Cheap hobby grade servos can sometimes chatter if they do not settle in a stable state. Th... | 709 | 2012-12-20T20:49:33.020 | |rcservo| | <p>I was working on a project to make a bedside night light out of a stuffed butterfly or bird. I was making a mechanism to make the wings flap with a servo motor and some small gears. The <a href="http://www.vexrobotics.com/276-2162.html">servo motor</a> was very loud as it moved. And this was whether or not the servo... | Why are Servo Motors so noisy? |
<p>The recently open-sourced <a href="http://www.coppeliarobotics.com" rel="nofollow">V-REP simulator</a> may suite your needs. I found it more approachable than Gazebo, and it can run on Windows, OSX, and Linux. Their tutorials are fairly straight forward. There are a ton of different ways to interface with it program... | 712 | 2012-12-20T22:33:51.033 | |mobile-robot|arduino|microcontroller|machine-learning|simulator| | <p>I'm currently building a robot with four legs (<a href="http://en.wikipedia.org/wiki/Quadrupedalism/" rel="nofollow noreferrer">quadruped</a>), 3 DOF (Degrees of Freedom) and Its been suggested <a href="https://robotics.stackexchange.com/questions/327/learning-algorithms-for-walking-quadruped/">here</a> that I use a... | Quadruped Learning Simulator |
<p><a href="http://www.pointclouds.org/" rel="noreferrer">PCL</a> has a nice C++ templated <a href="http://docs.pointclouds.org/trunk/group__sample__consensus.html" rel="noreferrer">RANSAC library</a> which can solve your problem.</p>
<p>If you feel, PCL is too big of a dependency, then using <a href="http://eigen.tux... | 716 | 2012-12-21T10:31:13.480 | |c++|ransac| | <p>Often when I need to perform model fitting I find myself looking for a decent C++ library to do this. There is the RANSAC implementation in <a href="http://reference.mrpt.org/svn/classmrpt_1_1math_1_1_model_search.html" rel="nofollow">MRPT</a>, but I was wondering if there are alternatives available.</p>
<p>To give... | C++ Robust Model Fitting Library |
<p>I tried using convex hull method, I found the convex hull of both the regions in 3D. Then, found the amount of intersection they have. If it is significantly high, then one object is lying inside the other. If it is not, then it may be on top of it, or may not be. So I tested that by finding the 2D convex hulls of b... | 718 | 2012-12-21T14:47:11.653 | |kinect|computer-vision|algorithm| | <p>How do we know that an object is contained inside another object or is just lying on top of it? </p>
<p>Lets take an example of a cup-plate-spoon. The cup is lying on top of the plate. But the spoon is inside the cup. How do we distinguish between the 2 situations? What are the criteria to decide whether A is conta... | How can computer vision distinguish one object being contained by another vs being on top of it? |
<p>This seems to work correctly and is a much simpler solution:</p>
<pre><code>function [X, FVAL, EXITFLAG, OUTPUT, GRAD] = join_maps(m1, m2)
p = [m1(1:3);m2(1:3)];
x1 = [p;m1(4:end)];
x2 = [p;m2(4:end)];
guess_0 = zeros(size(x1,1),1);
q = @(x)x'*eye(length(x))*x;
fit = @(x)q(x1-x)+q(x2-x);
... | 725 | 2012-12-24T00:50:05.517 | |slam| | <p><strong>There is a lot of background here, scroll to the bottom for the question</strong></p>
<p>I am trying out the map joining algorithm described in <a href="http://services.eng.uts.edu.au/~sdhuang/Shoudong_IROS_2010.pdf">How Far is SLAM From a Linear Least Squares Problem</a>; specifically, formula (36). The c... | Least squares map joining |
<p>Assuming the map is a point cloud and that you know the alignment between the ground truth data and the map then calculating the <a href="http://en.wikipedia.org/wiki/Mean_squared_error">mean squared error</a> (MSE) would give you a relative understanding of the accuracy. A lower MSE would indicate they are very sim... | 734 | 2012-12-28T16:47:56.377 | |slam|mapping| | <p>When you've created a map with a SLAM implementation and you have some groundtruth data, what is the best way to determine the accuracy of that map? </p>
<p>My first thought is to use the Euclidean distance between the map and groundtruth. Is there some other measure that would be better? I'm wondering if it's al... | Comparing maps to groundtruth |
<p>I know I'm digging up an old thread and this is sort of off topic, but I don't think you can just get hold of ET1200 chips from Beckhoff. I emailed them a little while back and was advised that I need to join the Ethercat group. To do this I had to demonstrate that I was going to contribute back to the group - ie, b... | 736 | 2012-12-29T17:06:37.283 | |microcontroller|electronics|communication|robotic-arm| | <p>I'm building a hobby 6-DOF robotic arm and am wondering what the best way is to communicate between the processors (3-4 AVRs, 18 inches max separation). I'd like to have the control loop run on the computer, which sends commands to the microprocessors via an Atmega32u4 USB-to-??? bridge.</p>
<p>Some ideas I'm consi... | Inter-processor communication for robotic arm |
<p>The lag in the compass is because of a low-pass filter, to suppress high frequency noise. </p>
<ul>
<li>There exist more expensive magnetometers which have less noise, and therefore, less lag.</li>
<li>It is also possible to use a gyroscope to improve accuracy. In fact, this is what Inertial Measurement Units (IMUs... | 738 | 2012-12-31T01:09:06.787 | |sensors|compass| | <p>I've got a tread-driven robot, with low precision wheel encoders for tracking distance and an electronic compass for determining heading. The compass has significant (> 1 second) lag when the robot turns quickly, e.g. after reaching a waypoint — pivoting in place to point to its new heading. </p>
<p>What ar... | What are methods for dealing with compass lag (rate dependent hysteresis)? |
<p>Yes, such a method can give you a reasonable estimates of noise. Note that it is susceptible to systematic error. For instance if you are flying a quadrotor in the presence of a fan. This would show up in your findings which is generally undesirable.</p>
<p>With that said you could improve your estimates by using th... | 741 | 2013-01-01T22:39:17.693 | |noise|ekf| | <p>I've seen <a href="https://robotics.stackexchange.com/questions/18/what-are-good-methods-for-tuning-the-process-noise-on-kalman-filters">this question</a>, which asks about determining the process noise for an EKF. I don't see anything there about pre-recorded data sets. </p>
<p>My thought on how to determine the... | How do you determine EKF process noise for pre-recorded data sets? |
<p>Forgive me I seem to get caught up in people looking for answers to a question they didn't ask a few times already. So given this question; </p>
<p>"How do I determine how many amps will be needed from the power supply?"</p>
<p>You can roughly guess it, in your case you say 4 servos drawing an amp each, 4 amps tot... | 748 | 2013-01-05T02:37:24.810 | |design|power|rcservo|bec| | <p>I'm trying to power 7-12 <a href="http://en.wikipedia.org/wiki/Servo_%28radio_control%29" rel="nofollow">servos</a>, and I was under the impression that each one would need about an amp, but in looking around for an appropriate <a href="http://en.wikipedia.org/wiki/Battery_eliminator_circuit" rel="nofollow">BEC</a> ... | How many amps do I want my Switching BEC to provide? |
<p>I think I see where you're confused, and you're correct in noticing that the motor variables are a little different than regular variables.</p>
<p>The <code>#pragma config( )</code> is actually doing a <em>lot</em> of heavy lifting for you because it is a "<a href="http://www.cplusplus.com/doc/tutorial/preprocessor... | 751 | 2013-01-05T09:00:41.440 | |robotc| | <p>I'm trying to program advanced functions in <a href="http://www.robotc.net/wiki/VEX2_Functions_Motors_and_Servos#motorType" rel="nofollow">RobotC</a> but I'm not too sure I'm doing it right. I want to specify the motor port I'm using, but I assigned names to all the motors. Funny thing though, they don't exactly wor... | Confused about the variables in RobotC? |
<p>I test positive for aspergers syndrome on highly validated tests and I can read facial expressions sufficiently well to notice certain patterns in my daily interactions and one of the most noticeable "common" patterns is the disgust/revulsion pattern. The sequencing is pretty simple, I start talking, within 500ms of... | 758 | 2013-01-07T21:09:56.563 | |research|hri|uncanny-valley| | <p>I'm familiar with the idea of the <a href="http://en.wikipedia.org/wiki/Uncanny_valley" rel="nofollow">uncanny valley</a> theory in human-robot interaction, where robots with <em>almost</em> human appearance are perceived as creepy. I also know that there have been research studies done to support this theory using ... | In HRI, how is the "uncanny valley" experienced by people on the autism spectrum? |
<p>You are correct in that there is no Kinematic difference. </p>
<p><a href="http://en.wikipedia.org/wiki/Kinematics" rel="nofollow">Kinematics</a> do not consider why things happen - ie dynamic stability.</p>
<p>There are obvious physical differences, but when the math is worked out for kinematics, it should be the... | 763 | 2013-01-09T00:41:35.487 | |mobile-robot|design|kinematics|theory| | <p>I got the following homework question:</p>
<blockquote>
<p>What are the general differences between robots with Ackermann steering and standard bicycles or tricycles concerning the kinematics?</p>
</blockquote>
<p>But, I don't see what differences there should be, because a car-like robot (with 2 fixed rear whee... | Differences between Ackermann steering and standard bi/tricycles concerning kinematics? |
<p>As it says in the description of the file format, it is for graph based SLAM approaches. These work on minimizing the error of a pose constraint network. You can think of it this way: There are a number of reference frames (your vertices) and then you have knowledge on the transformation between these frames. These ... | 764 | 2013-01-09T03:56:58.867 | |slam|mapping| | <p>I am most familiar with SLAM maps that are point clouds, usually in the form of a vector like $<x,y,\theta,f_{1x},f_{1y},...,f_{nx},f_{ny}>$. I also understand how to create a map like this using an EKF.</p>
<p>Today I came across a <a href="http://www.mrpt.org/Graph-SLAM_maps">.graph file format</a>, which ... | The relationship between point cloud maps and graph maps |
<p>I believe a little Googling and you will find several of the existing controller boards have open source. For example I made a small change to <a href="http://www.hobbyking.com/hobbyking/store/__24723__Hobbyking_KK2_0_Multi_rotor_LCD_Flight_Control_Board.html" rel="noreferrer">hobby kings KK board</a> last week, com... | 768 | 2013-01-10T05:53:51.920 | |balance|quadcopter| | <p>I'm using my own code to create a quadcopter robot. The hardware part is done but I need to balance the copter. </p>
<p><sup>The original video demonstrating the problem was shared via dropbox and is no longer available.
</sup></p>
<p>I have tried to play with the speed of each motor to get it balanced. It didn't ... | How to balance a flying quadcopter? |
<p>this page gives a nice overview of joint torque requirements for robot arms. and even provides a simple calculator. <a href="http://www.societyofrobots.com/robot_arm_tutorial.shtml" rel="nofollow">http://www.societyofrobots.com/robot_arm_tutorial.shtml</a></p>
| 775 | 2013-01-10T21:41:04.937 | |design|otherservos|robotic-arm| | <p>I would like to design a robotic arm to hold a weight X at length Y (in my case I want to hold X=2.5 lbs at Y = 4 inches). Starting out simply, I would like try building an arm with a gripper plus one servo joint. </p>
<p>[Servo Joint] ----- Y ------ [Gripper] </p>
<p>When designing an arm, would I want to say th... | Getting started with robotic arm design |
<p>The industry standard for solving this problem is with <a href="https://www.google.com/search?q=moving+faders&hl=en&tbo=u&tbm=isch&source=univ&sa=X&ei=Pg4KUfqlI-r7iwKmpYDYCQ&ved=0CH4QsAQ&biw=1710&bih=1145" rel="nofollow noreferrer">moving faders</a>.</p>
<p><img src="https://i.st... | 777 | 2013-01-11T02:30:04.570 | |motor|otherservos| | <p>I am trying to build a semi-analog timer. Something like those old egg timers that you rotate the face of. I want a knob that I can turn that can be read by a microcontroller, and I also want the microcontroller to be able to position the knob. I'd like to implement "stops" by letting the microcontroller push the kn... | Building a controllable "knob" |
<p>Your first 2 reasons for having a robot are still wrong today, that is 2 years after you posted.</p>
<ol>
<li><p>There are no AI algorithms so far. What currently exists are somewhat smart action-reaction scenarios. I've been working in crane automization in a cement plant between 1997 and 2000. Various sensors sen... | 780 | 2013-01-11T15:07:34.650 | |mobile-robot| | <p>The fact is that the more I search the less I find autonomous (real) robots in use. The companion robots are all toys with limited useless functionality. Whenever there is a natural disaster you don’t see operational search and rescue robots in the news. Even military robots in service are all remotely controlled ma... | What are the reasons for not having autonomous robots in our daily activities? |
<p>The branch of science that most closely resembles "nano bots" is <a href="http://en.wikipedia.org/wiki/Capsule_endoscopy" rel="nofollow noreferrer">Capsule Endoscopy</a>. </p>
<p><img src="https://i.stack.imgur.com/S6htU.jpg" alt="Camera Pill"></p>
<p>The first generation of these were just "edible" video cameras... | 788 | 2013-01-13T05:01:51.300 | |mobile-robot| | <p>I was wondering, do we have real nano bots, like the ones in the movies? </p>
<p>I think we have bots which can move through the blood vessels, am I right?</p>
| Do "nano bots" (that can fit inside the human body) actually exist? |
<p>In general, toy robots probably face fewer challenges, except in human safety. I'd imagine that they don't usually advance the knowledge base themselves.</p>
<p>HOWEVER, I think it's beyond question that our crop of engineers and scientists will be larger and more competent if they're exposed early and often to tec... | 790 | 2013-01-13T18:38:55.450 | |research| | <p>Over the last month, I saw many robots that don't have any real purpose, which made me ask myself: "Does this have any value?" I saw dancing robot on CES, advanced lego based robots and also robots combined for very limited purpose. I saw ten year old children playing with robots, and competitions for them. Someone ... | Do "toy" robots move technology forwards? |
<p>After some conversations with Microhard's technical support, the following procedure worked for me:</p>
<ol>
<li>Email Microhard technical support. Explain what you're trying to do, and ask for a version of 920 series firmware that will communicate with your 910 series modem. This firmware is available for the n9... | 795 | 2013-01-14T14:40:31.087 | |radio-control| | <p>Microhard Systems currently sells several types of 900MHz modems, which are mostly used in robotics and SCADA applications. One of their product lines, the 910 series (MHX910, n910, Spectra 910), is obsolete and no longer sold. However, some older equipment is built with OEM versions of the 910 series soldered in ... | How can Microhard 920 series modems be made compatible with Microhard 910 series? |
<p>Really this is a question to be answered by experiments. Will it work? It seems like it could. Two things that will be important to look at are:</p>
<ol>
<li><em>Training time</em> - You are still using a neural network and they take time to train. Whether this formulation would reduce the number of rounds required... | 801 | 2013-01-16T10:41:52.210 | |microcontroller|machine-learning|walk| | <p>I'm building a quadrupedal robot that will learn how to walk. From the <a href="https://robotics.stackexchange.com/questions/568/is-it-possible-to-run-a-neural-network-on-a-microcontroller">responses</a> I got from asking if its possible to run a NN on a micro controller I realised I needed to think of a clever sys... | Simple Neural Network with hardcoded positions for walk optimisation |
<p>You seem to have 2 separate (but related) problems you are trying to solve at once. Let's break down your conundrum into smaller pieces:</p>
<ol>
<li>How do I <em>communicate</em> commands from a slow system (30Hz) to a fast controller (200Hz), and how do I communicate data being received at 200Hz back to my 30Hz t... | 807 | 2013-01-17T08:50:58.617 | |control|design|communication| | <p>We are currently designing a mobile robot + mounted arm with multiple controlled degrees of freedom and sensors. </p>
<p>I am considering an architecture in two parts:</p>
<ol>
<li><p>A set of realtime controllers (either Raspeberry Pis running an RTOS such as Xenomai or bare metal microcontrollers) to control the... | How can I control a fast (200Hz) realtime system with a slow (30Hz) system? |
<p>The underlying microcontroller in the VEX Cortex is some sort of STM32F1 or STM32F2. I'm not sure which model exactly (just that it's a ST-made Cortex M3), but they all do have digital I/O capabilities on the pins used for analog inputs. Given the bare microcontroller, you could do so.</p>
<p>However, the VEX Corte... | 810 | 2013-01-17T23:17:15.437 | |sensors| | <p>I'm running out of digital ports, and have no sensors that fit the definition 'analog'. Would it be possible to run a <a href="http://www.robotc.net/support/vex/WebHelpCortex/index.htm#page=functions_vex/sensors/VEX_2.0_Cortex_-_Sensors.htm">touch sensor, a quadrature encoder, or an ultrasonic sensor on an analog po... | Can ultrasonic and button sensors be run in a VEX analog port? |
<p>I would suggest you to check the HC-SR04 Ultrasonic Sensor that could easily wired and programmed into your robo vehicle. By adjusting the sensor to correctly emit ultrasound on a fixed object and measuring echo/ping from the object, you can judge the distance quite accurately.
<a href="https://i.stack.imgur.com/aTw... | 812 | 2013-01-18T13:37:18.247 | |mobile-robot|arduino|sensors| | <p>I have a small motorized vehicle with gears as wheels running up and down a track made of gear racks. How can this robot know when it has run half the track? And what's the best method to keep it from running off its track at the end and then return to start.</p>
<p>The robot is carrying water, not exactly the same... | How to find out how far a motor has taken a vehicle? |
<p>Is the problem that the off-the-shelf motor shields all look like they mechanically interfere with the other shield you want to use?
Perhap you're seeing the "both shields want to be the top shield, so they can't stack" problem?
It's pretty simple to control servo motors with simple wire connections.</p>
<p>Standar... | 815 | 2013-01-18T19:08:37.780 | |control|arduino|microcontroller|motor|power| | <p>I'm working on a rather low budget project, and need some way to control four or more motors using one Arduino. I've looked at motor shields a little, but I have a shield on top of it already, It does have female input on the top though, so a motor shield may work. Any suggestions?</p>
| Arduino Motor control |
<p>An <a href="https://www.google.com/search?q=optical%20encoder%20disk&hl=en&tbo=u&tbm=isch&source=univ&sa=X&ei=hvv8UKSBEMraigLkg4GQBA&ved=0CFkQsAQ&biw=1524&bih=1088" rel="nofollow noreferrer">optical encoder</a> is fairly simple to add to an existing wheel.</p>
<p><img src="https:... | 819 | 2013-01-21T06:25:29.593 | |arduino|microcontroller| | <p>We have an electric wheel chair, and are looking to add a rotary encoder to each wheel. We don't want to hack the motor itself, so want to add the encoder without harming the motor-to-wheel connection. We will be using an arduino to read the signal.</p>
<p>Does anyone have any experience adding rotary encoders to... | Adding Rotary Encoders to an Electronic Wheel Chair |
<p>Your question is not clear. "Is this byte array converted from hex?" If you know what the values are, you should know how you got them. 128 is not a hex number, it is the same as a hex 80, also written as 0x80. It indicates a 'Direct command, reply not required' as a serial to NXT stream. 15 = 0x0F = LSWRITE.</p>
... | 832 | 2013-01-25T13:51:19.353 | |nxt|i2c| | <p>I have been trying to write code to connect a <a href="http://www.hitechnic.com/cgi-bin/commerce.cgi?preadd=action&key=SPR2010" rel="nofollow">HiTechnic prototype board</a> to my lego brick. Although I am using MSRDS studio, that isn't the issue; reading and writing to the serial port that the device is connecte... | How do I interpret this data, received by the I2C controller on an NXT 2 brick? |
<p>To expand on <a href="https://robotics.stackexchange.com/a/842/37">thisismyrobot's answer</a>, beam width is indeed important. However, there are a number of other factors, such as the reflectivity of the environment (acoustic "brightness"), transmission frequency, etc.</p>
<p>Although it is from 1988, <a href="ht... | 839 | 2013-01-26T17:51:53.783 | |mobile-robot|sensors|navigation|acoustic-rangefinder| | <p>For avoiding obstacles during 2D robot navigation what is the best position/angle to place the sonar sensors? How many should there be?</p>
<p>I would like to know if there is some theory or examples for the problem of placing. I realize that it depends on the way that the robot moves and its geometry, but I am sea... | Sonar for obstacle avoidance: how many sensors and where to place them? |
<p>As mentioned above 7-bits means possibility of 128 slave devices attached to the same i2c bus.</p>
<p>This loop is run 128 times(0-127) to determine how many slaves are present on the bus by asking them to respond(via ack) and prints whenever a device presence is detected. </p>
| 848 | 2013-01-29T14:06:09.987 | |arduino|i2c| | <p>I am learning about I2C on the Arduino. I was looking at a sample program to scan for I2C devices and saw this:</p>
<pre><code>// This sketch tests the standard 7-bit addresses
// from 0 to 127. Devices with higher bit address
// might not be seen properly.
</code></pre>
<p>With the following code. </p>
<pre><cod... | Why must I loop 127 times for a "7-bit" address in this example? |
<p>I put together encoders for this exact chassis. Rather than reflecting ones, I used slot ones. I thought I could work off the hole in the white gear, but it turns out the plastic is pretty transparent to IR, so I ended up using some black electical tape (high tech, I know) to make opaque regions on the gear. </p>... | 854 | 2013-01-30T03:44:23.420 | |arduino|two-wheeled| | <p>I have the following chassis along with an Arduino and a motor shield. <img src="https://i.stack.imgur.com/DgPKZ.jpg" alt="Robot Chassis"></p>
<p>I'm in the process of developing a tracking mechanism for use with differential drive.</p>
<p>Normally, a photo reflector can be placed adjacent to the wheel that will r... | Sensors for differential drive |
<p>While this can be done it will be problematic. The issue comes from the fact that particle filters are a method for dealing with multi-modal probability distributions (PD) while Kalman filters assume your PD can be well represented with a Gaussian distribution.</p>
<p>I can conceive of a few methods for doing so if... | 857 | 2013-01-30T16:03:51.357 | |localization|kalman-filter|particle-filter| | <p>Is there a way of initializing a Kalman filter using a population of particles that belong to the same "cluster"? How can you determine a good estimate for the mean value (compute weighted average ?) and the covariance matrix ? Each particle is represented as $[ x , y , θ , weight]$.</p>
| Can you seed a Kalman filter with a particle filter? |
<p>As a child I had a copy of a software called "<a href="http://www.mhj-tools.com/sps-visu/" rel="nofollow" title="SPS VISU">SPS Visu</a>" where you could do such simulations. (I thought it was a game and sure ha a lot of fun with it :D) Maybe this is what you are looking for?</p>
| 863 | 2013-01-31T10:58:41.593 | |simulator| | <p>I need to simulate a stream of vehicles, such as on an assembly line. Automatons are performing operations on the vehicles when they come within reach. The automatons do not keep track of the individual vehicles, they simply collect data.</p>
<p>We need to choose a method of matching the data gathered by each auto... | How do I simulate an assembly line? |
<p>To detect if your steppers have stalled check this question<a href="https://robotics.stackexchange.com/questions/1270/how-to-detect-when-a-stepper-motor-has-stalled/1271?noredirect=1#comment2845_1271">how to detect when a stepper motor has stalled</a>. </p>
<p>If you want to use absolute positioning you can create ... | 865 | 2013-02-01T00:06:46.373 | |arduino|stepper-motor|current|cnc| | <p>I am creating a CNC machine on a budget, using old motors out of printers/scanners/etc. </p>
<p>I am limited to about 650mA for the whole system, so my fear is that when the cutting bit touches the material, the stepper might be moving too quickly and won't have enough torque. This would mean it will become one ro... | How to tell a stepper motor's position, or detect slippage |
<p>This looks very much like a simplification of a traditional <a href="http://en.wikipedia.org/wiki/SCARA" rel="nofollow">SCARA</a> robot design.</p>
<p>It is a nice simple design in which the weight bearing axes are all nicely horizontal, which means these axes behave similarly irrespective of the load weight. The o... | 869 | 2013-02-03T21:22:36.800 | |design|robotic-arm|joint| | <p>I am very new to robotic design and I need to determine what parts I will need to assemble an arm joint. The joint will contain one timing belt pulley which a remote motor will be turning, a forearm that the pulley will be rotating and an upper-arm piece that will actually be two parallel arms that will grip the pu... | Building Robotic arm joint |
<blockquote>
<p>Am I correct in saying that this would not require a gyro, just a 3 (2?) axis accelerometer, to detect pitch and roll, then adjust the ailerons and elevator to compensate?</p>
</blockquote>
<p>No. The opposite is true. The accelerometer will be almost useless to detect rotations on a platform that's ... | 872 | 2013-02-04T07:16:00.323 | |uav|accelerometer|imu|gyroscope| | <p>I'm working on a basic airplane flight stabilization system, as the precursor to a full autopilot system. I'm using a salvaged Wii Motion Plus and Nunchuk to create a 6DOF IMU. The first goal is to keep the wings level, then mix in the users commands. Am I correct in saying that this would not require a gyro, just a... | Do I really need a gyro for an airplane flight stabilization system? |
<p>A DC motor has 2 directions, <code>forwards</code> and <code>backwards</code>.</p>
<p>The DC motor <strong>does not</strong> control the direction of an RC car, instead it's the <strong>steering mechanism</strong>.</p>
<p>Rather than write everything here - I have found <a href="http://rc4beginners.blogspot.co.nz/... | 876 | 2013-02-02T23:41:45.237 | |control|wheel| | <p>Before I start asking you for help let you know that I am newbie in electronic field.</p>
<p>All I want to know is the principle of wheel rotation (left-right) from remote car gadget. I am not talking about changing the spin rotation of DC motor (up,down buttons from remote), I am asking about left and right moveme... | Remote car controlling |
<p>What I've found 3d printing with SketchUp:</p>
<ul>
<li><p>Use good geometry. Free Drawing should pretty much <strong>never</strong> be used. Make sure all of your arcs & angles are clean.</p></li>
<li><p>You can <strong>not</strong> have unclosed areas. Some programs are very good about this. Sketchup is <stro... | 878 | 2013-02-05T06:36:50.580 | |3d-printing| | <p>I have 3D printers at my school, but unfortunately they are not super high quality. I want to try 3D printing a model I made on google sketchup, but I would like for it to be fairly accurate.</p>
<p>What measures can I take to prevent error in the model? I understand that I need to export the file as an STL; is the... | Accurate 3D Printing W/Sketchup |
<p>Some years ago I have used the supervisor to know the position of a simulated Khepera robot in Webots 4.
The main components of the C code was the following:</p>
<p>Declarations:</p>
<pre><code> #define STEP 64
NodeRef robot_node;
float robot_data[4]={0,0,0,0};
</code></pre>
<p>Getting the node named Kheper... | 883 | 2013-02-06T10:36:06.213 | |mobile-robot|simulator|reinforcement-learning|webots| | <p>I have been experimenting with different fitness functions for my <a href="http://www.cyberbotics.com/overview" rel="noreferrer">Webots robot simulation</a> (in short: I'm using genetic algorithm to evolve interesting behaviour).</p>
<p>The idea I have now is to reward/punish Aibo based on its speed of movement. Th... | Measuring speed of movement in Webots |
<p>Per the schematics of the UltraSonic Sensor the P1.3/SCL is DIGIAI0 or J1.5 and P3.0/SDA is DIGIAI1 or J1.6. And the developer Kit Manual states it is I2C as per philips original standard, detailing all the memory address's of the ESC015 chip and with all the recommended interfacing circuitry. The only note that I s... | 885 | 2013-02-07T03:57:22.483 | |arduino| | <p>Does anyone know if this is possible? It's just an i2c device right? I mean you would have to cut the cable and make it so you could plug into the pins on the Arduino but you should just be able to use the wire library and say something like. </p>
<pre><code>Wire.beginTransmission(0x10);
</code></pre>
<p>the NXT h... | Would is be possible to connect a HiTechnic prototype board to an Arduino? |
<p>It is not possible to achieve <em>arbitrary</em> precision in camera calibration, precisely because of camera resolution and camera imperfections (e.g. lens distortion, which is only approximated in the calibration of intrinsic parameters). </p>
<p>That, however, isn't usually the worst part of the deal. You can go... | 892 | 2013-02-08T17:27:08.697 | |computer-vision|calibration| | <p>Is it possible to achieve arbitrary precision to the calibration of the extrinsic parameters of a camera or is there a minimum error wich can not be compensated (probably dictated by the camera's resolution)?</p>
| Is it possible to achieve arbitrary precision in camera calibration? |
<p>And for the 'I'd rather be designing the sensors and grippers' of us, consider a ready made motor shield for Arduino such as:</p>
<p><a href="http://www.pololu.com/catalog/product/2504" rel="nofollow noreferrer">Polulu Zumo Shield</a> (1.2 amp motors) or the <a href="http://arduino.cc/en/Main/ArduinoMotorShieldR3" ... | 897 | 2013-02-09T22:36:37.333 | |arduino|motor| | <p>I'm trying to control a higher voltage motor than an arduino can source with a pin, with an arduino. I am trying to hook it up to a transistor. The battery pack is not supposed to be 4.8V, it's 6V, 4 D batteries.</p>
<p>Here is the setup:</p>
<p><img src="https://i.stack.imgur.com/m9QPz.png" alt="Circuitry setup">... | High voltage motor control with arduino |
<p>It would be interesting if they would have these hard anodized, which would give the surface of the aluminum the same hardness as case-hardened steel. I agree though that the contact area is very small. I do not see the advantage of this over an undercut slot that captures a t-nut underneath, which would still give ... | 908 | 2013-02-11T23:41:06.083 | |mechanism|kit| | <p>I've been looking into a <a href="http://www.makeblock.cc/" rel="nofollow noreferrer">Makeblock robotics kit</a> but have found no information on the web that comes from end-users, and one of the main advertised features is not clear to me: The slot threads shown below are straight, while the screw thread that will... | How does the Makeblock threaded slot work? |
<p>While the answer by <a href="https://robotics.stackexchange.com/a/914/37">freeman01in</a> references a <a href="http://www.scribd.com/doc/38698/Sizing-Electric-Motors-for-Mobile-Robotics" rel="nofollow noreferrer">useful presentation</a> (<a href="http://in.docsity.com/en-docs/Sizing+Electric+Motors+for+Mobile+Robot... | 913 | 2013-02-12T16:16:00.323 | |mobile-robot|design|motor| | <p>I am designing a new platform for outdoor robotics and I need to calculate the power and/or torque that is needed to move the platform. I have calculated that I need about 720 W of total power to move it (360W per motor), but I don't know how to calculate the torque that I need. </p>
<p>Is it really just about havi... | Are power and torque required related in some way? |
<p><strong>Can Kinect data be stored directly onto a USB drive?</strong></p>
<p>Yes. In ROS that would be easily done using bag files. In Windows, however, you might have to look for something native in the Microsoft SDK/OpenNI or code it yourself. <em>Edit: In OpenNI there is something called .oni files for that purp... | 918 | 2013-02-14T09:59:40.490 | |kinect|ros| | <p>Does anybody know if Kinect Data can be stored directly onto a USB Drive??
I have a Kinect for Windows that i cannot use on Linux(ROS). However what i plan is to mount the Kinect on my robot, store the captured frames on a USB and then un mount the USB ,transfer to Linux and process them on ROS.</p>
<p>Is this pos... | Storing Kinect Data on a USB Drive |
<p>Yes , it is possible but please note the following points.</p>
<p>1)if you are using Bluetooth, it data transfer rate depends upon different versions like for v2 blue tooth its data transfer rate 3 Mb\s.</p>
<p>2)Now let suppose you are using a camera like ov7670 in QVGA mode(320 x 240 pixels for one frame) each p... | 921 | 2013-02-14T16:56:23.807 | |arduino|cameras| | <p>I'm trying to connect a camera module to my Arduino Mega, connect my Mega to my Android phone (throught BlueTooth or other), and send the live view of the camera to the mobile phone.</p>
<p>I saw a <a href="http://www.youtube.com/watch?v=qEVXqOJz-GY">video online</a> that showed this for still images -- an image ca... | How can I send video from my Arduino camera module video to my Android screen? |
<p>According to TI's website, <a href="http://www.ti.com/general/docs/wtbu/wtbuproductcontent.tsp?templateId=6123&navigationId=12828&contentId=50020" rel="nofollow noreferrer">some of the OMAP processors (specifically the OMAP-DM5x range) have stacked RAM</a>.</p>
<p><img src="https://focus.ti.com/en/multimedi... | 924 | 2013-02-15T08:20:41.940 | |arm-cpu| | <p>Do any of the TI <a href="http://en.wikipedia.org/wiki/ARM_system-on-chip_architecture" rel="nofollow">ARM SOC</a>s, e.g. <a href="http://www.ti.com/lsds/ti/arm/sitara_arm_cortex_a_processor/sitara_arm_cortex_a8/omap3503_15_arm_cortex_a8/products.page?paramCriteria=no" rel="nofollow">OMAP</a> or <a href="http://www.... | TI ARM with stacked RAM |
<p>This guy put a spring in between his 2nd servo to protect them from any slight differences... Maybe this is what you're looking for? <a href="http://youtu.be/jqsmai2Nafk?t=1m13s" rel="nofollow">http://youtu.be/jqsmai2Nafk?t=1m13s</a></p>
| 939 | 2013-02-17T21:09:19.683 | |motor|rcservo| | <p>For my robot, I am using two continuous rotation servos to spin a threaded rod. I am trying to make this project as cheap as possible. Here are the servos that I can find:</p>
<ul>
<li>Servo #1: This is a very cheap option and it has half of the torque I need.</li>
<li>Servo #2: This has all of the torque my projec... | Will connecting two servo motors double the torque? |
<p>The <a href="http://en.wikipedia.org/wiki/Denavit%E2%80%93Hartenberg_parameters" rel="nofollow">DH Matrix</a> section of the DH page on wikipedia has the details.</p>
<p>Basically you want to use the information in your table to create a set of homogeneous transformation matrices. We do so because homogeneous trans... | 940 | 2013-02-18T11:18:22.693 | |kinematics|forward-kinematics| | <p>I'm doing robotics research as an undergraduate, and I understand the conceptual math for the most part; however, when it comes to actually implementing code to calculate the forward kinematics for my robot, I am stuck. I'm just not getting the way the book or websites I've found explain it.</p>
<p>I would like to ... | How do I convert link parameters and angles (in kinematics) into transformation matrices in programming logic? |
<p>In the end, I found that the best way to do this was to employ a very simple concept: <a href="https://en.wikipedia.org/wiki/Flood_fill" rel="nofollow">Flood Fill</a>. I used a <a href="https://en.wikipedia.org/wiki/Flood_fill#Alternative_implementations" rel="nofollow">stack-based iterative approach</a> instead of... | 952 | 2013-02-19T21:02:05.790 | |algorithm|coverage|planning| | <p>I'm trying to create a map of the obstacles in a fairly coarse 2D grid space, using exploration. I detect obstacles by attempting to move from one space to an adjacent space, and if that fails then there's an obstacle in the destination space (there is no concept of a rangefinding sensor in this problem).</p>
<p><... | What's an efficient way to visit every reachable space on a grid with unknown obstacles? |
<p>As Plecharts said, it depends on your surface. Magnets work really well for a heavy robot, but iff you're going to drive on metal. An example can be found on this VEXLabs robot: <a href="http://www.vexforum.com/wiki/Magbot_Model_3" rel="nofollow">http://www.vexforum.com/wiki/Magbot_Model_3</a></p>
| 957 | 2013-02-20T14:54:30.407 | |mobile-robot| | <p>I have come across a number of methods for developing wall-climbing robots.</p>
<ul>
<li>Suction</li>
<li>Chemical Adhesion</li>
<li>Gecko like hair adhesion</li>
<li>Electroadhesion</li>
</ul>
<p>Which method would be the best for heavy robots (5kg+)? Are there any other methods that I have missed?</p>
| Adhesion for a heavy wall-climbing robot |
<p>To your first question: "Does the same apply when using the odometry motion model?", the answer is Yes.</p>
<p>The the EKF is pretty much the same thing as the KF, with the addition of the linearization step. What you are linearizing here is the motion model, whatever model that is. </p>
<p>For your second quest... | 964 | 2013-02-21T13:50:43.330 | |localization|kalman-filter| | <p>In the prediction step of EKF localization, linearization must be performed and (as mentioned in <a href="http://books.google.co.uk/books/about/Probabilistic_Robotics.html?id=k_yOQgAACAAJ&redir_esc=y" rel="noreferrer">Probabilistic Robotics [THRUN,BURGARD,FOX]</a> page 206) the Jacobian matrix when using velocit... | Extended Kalman Filter using odometry motion model |
<p>On a semi related note, is there a possibly of permanent damage to the magnemometer and other chips if they are exposed to a magnetic field of between 1000-2000 uT from a stack of small rare earth magnets? I tried doing that to the 9-DOF IMU from adafruit today as a test and it seems to have permanently altered the ... | 970 | 2013-02-23T07:23:28.393 | |sensors|imu| | <p>Im in the process of making a robot which requires 12 3x10mm cylindric magnets for the construction. They are 30mm from the center of the robot where I plan to have the IMU. </p>
<p>I was thinking about using MPU-6050. Do magnets affect the values? If yes, is there a solution for it? like maybe I could have a shiel... | Do magnets affect IMU values? |
<p>I would suggest that the key reason is reliability - once a probe has been launched into space, it <strong>HAS</strong> to work.</p>
<p>As such, it is a lot safer to heat up a known, reliable, material that has been subject to extensive testing, than it is to "invent" a new material that cannot be fully tested on E... | 975 | 2013-02-24T12:18:01.820 | |heat-management|cooling| | <p>I know that temperature influences the characteristics of semiconductors and other materials, but we know how and can take that into account. Furthermore, lower temperatures makes electronics more efficient, sometimes even superconducting.</p>
<p>I remember reading somewhere that engineers building Curiosity even c... | Why do space probes need heating? |
<p>Triumphant</p>
<p>Check this out. Under normal circumstances you would configure your sensor by giving it a port. It would look like the following.</p>
<pre><code>pxbrick.Registration registration = new pxbrick.Registration(new LegoNxtConnection((LegoNxtPort)_state.SensorPort),
</code></pre>
<p>Well, inside of t... | 984 | 2013-02-25T21:13:25.777 | |nxt|i2c| | <p>Here is the background. I am trying to write a service for the HiTechnic prototype board. </p>
<p>Using the Appendix 2 from the blue tooth developers kit from Lego's site I am able to understand what is going on with this service I am trying to build however the response I get is always 221 = 0xDD = "Communication ... | Does anyone know what might be giving me this error coming from an i2c device |
<p>What kind of motors? ESCs typically are for brushless DC motors, which are electronically commutated DC three phase motors, and you can't run them with an H-bridge. </p>
<p>That said, ESCs give you a lot of bang for the buck, and they're certainly worth $12 :)</p>
| 985 | 2013-02-26T02:47:45.793 | |design|electronics|wheeled-robot| | <p>I was able to find a small ESC for about $12 off of ebay. If you were designing a robot, would you see that and think? </p>
<blockquote>
<p>\$12 bucks for an ESC that connects to simple pulse-wave interface -
sign me up!</p>
</blockquote>
<p>Or would you think:</p>
<blockquote>
<p>\$12 just to control a m... | Which is easier/cheaper: Hbridge vs ESC for controlling a motor? |
<p>You can use the INS / GPS as updates to the output of your first EKF. This is, in fact, not chaining, but simply conditioning the estimate based on the added information from the INS / GPS.</p>
<p>Suppose we have the following functions: </p>
<p>$x_{t+1|t}$, $P_{t+1|t}$ = EKF_PREDICT($x_t$, $P_t$, $u_t$), for inpu... | 994 | 2013-03-01T04:05:48.827 | |kalman-filter|imu|navigation| | <p>My team is building a robot to navigate autonomously in an outdoor environment. We recently got a new integrated IMU/GPS sensor which apparently does some extended Kalman filtering on-chip. It gives pitch, roll, and yaw, north, east, and down velocities, and latitude and longitude.</p>
<p>However, we also have some... | Chaining Kalman filters |
<p>Two issues on hardware,</p>
<p>a) Chip takes time to turn on and off. Heating up more while in-between on and off. So, no point to use too high frequency. Generally, 10, 15 or 20KHz max, out of human ear range is enough. </p>
<p>See details (explain frequency effects with examples of 20 chips from many companies)... | 998 | 2013-03-02T15:57:31.173 | |pwm|avr| | <p>We are making a junior soccer robot and we just got our brilliant motors from Maxon.
Setting the PWM timer to low-frequencies (around 39kHz or 156 kHz ) the robot acts as expected. But this produces some problems. </p>
<ol>
<li>It puts a heavy current on batteries (around 1.5A for 3 motors which is far too high).</... | Motors response different with high-frequency PWM |
<p>Holding torque, by the stepper motor definition, is not a valid way to quantify servo performance. Stepper motor torque drops off with speed whereas in a servo it remains relatively constant. (Operating torque is never half of holding torque and is RPM dependent, your guide lied to you).</p>
<p>A real servo will ... | 999 | 2013-03-02T17:54:46.930 | |rcservo|stepper-motor| | <p>I am following a guide that recommends using stepper motors and it has an approximate holding and operating torque. It says that if you don't know the operating torque, it is often half of the holding torque. I am adapting this to use with a servo and I was wondering can this same formula be used with a servo. My se... | For servos, can it be implied that `Holding Torque = Operating Torque * 2` like with steppers? |
<p>After the propagation step, we need to find the parameters of the Gaussian which describe our new estimate. These are, the mean $\mu$, and the co-variance $\Sigma$. You asked about the mean specifically, so here we go.</p>
<p>Note that the definition of the mean of the propagated state is the expectation of the pro... | 1006 | 2013-03-03T20:00:06.140 | |kalman-filter|theory|ekf| | <p>In <a href="http://www.probabilistic-robotics.org/" rel="nofollow">Probablistic Robotics by S. Thrun</a>, in the first section on the Extended Kalman Filter, it talks about linearizing the process and observation models using first order Taylor expansion. </p>
<p>Equation 3.51 states:</p>
<p>$g(u_t,x_{t-1}) \appr... | Taylor Series expansion for EKF |
<p>It sounds like you're planning to create a 2×2 configuration of individual cells, which is a common configuration:
<a href="https://i.stack.imgur.com/q5qFK.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/q5qFK.jpg" alt="4 pack 6.4V lithium battery" /></a><br />
<sub>(source: <a href="http://img.di... | 1011 | 2013-03-04T14:46:52.133 | |battery| | <p>I'm looking to use 4 of <a href="http://www.batteryspace.com/lifepo426650cell32v3300mah16.5arate10whunapproved.aspx" rel="nofollow noreferrer">these 3.2V LiFePO4 batteries</a>. I intend to have 2 pairs of 2 in series in parallel. So two 6.4V battery packs in parallel. Because my setup will be run off of this, it wil... | Charging multiple LiFePO4 batteries at the same time? |
<p>I've made a small robot that follows a virtual path drawn on a smartphone under an NSF funded research grant.</p>
<p>The way you would make a robot follow a virtual path is to use the Pure Pursuit path following algorithm along with dead reckoning.</p>
<p>I developed the following C++ Arduino libraries for virtual r... | 1020 | 2013-03-07T15:52:55.750 | |mobile-robot|localization|wheeled-robot|industrial-robot|line-following| | <p>I would like to build a robot which follows a virtual path (Not a visible path like a 'black line on a white surface', etc).</p>
<p>I'm just enthusiastic by seeing some sci-fi videos which show robots carry goods and materials in a crowded place. And they really don't follow a physical line. They sense obstacles, d... | How to make an "invisible line following robot"? |
<p>Servo technology has evolved a lot over the last few years.<br />
You can check out this video showcasing metal servos that power Petoi open source robot dog Bittle:
<a href="https://www.youtube.com/watch?v=FRE-sp05ia8" rel="nofollow noreferrer">https://www.youtube.com/watch?v=FRE-sp05ia8</a>
These digital servos ar... | 1023 | 2013-03-08T08:44:20.903 | |rcservo|walking-robot| | <p>I'm building a quadruped and I'm not sure of the features I should be looking for in a servo motor. e.g. digital vs analog, signal vs dual bearings. Some of the ones I'm considering are <a href="http://www.servodatabase.com/compare?servos=806,1660,1664,1666http://www.servodatabase.com/compare?servos=806,1660,1664,16... | Servo motor considerations for a quadruped |
<p>A PID loop and a so-called PIV loop with equal gains should have the same response to a disturbance, so I'm not sure why the claim that the disturbance response is better or worse.</p>
<p>As mentioned, the derivative "kick" will be less, which can be a good thing if you give the thing sharp inputs.</p>
<p>In addit... | 1032 | 2013-03-09T15:52:12.467 | |control|otherservos|pid| | <p>I'm considering experimenting with PIV control instead of PID control. Contrary to PID, PIV control has very little explanation on the internet and literature. There is almost a single source of information explaining the method, which is a <a href="http://parkermotion.com/whitepages/ServoFundamentals.pdf">technical... | How is PIV control performed? |
<p>If you are speaking about RC style servos, then the actual drive to the motor is in the form of a pulse width modulated voltage: the servo amplifier just turns the motor on fully in one direction or the other, for a length of time determined by the difference between the measured position and the target position as ... | 1033 | 2013-03-09T17:01:12.603 | |otherservos|pid| | <p>I'm trying to learn about servo control. I have seen that the most generic position control method for servos is PID, where the control input is position error. However, I am not sure about what is the actuated quantity. I am guessing that it is one of:</p>
<ul>
<li>Voltage applied to the motor</li>
<li>Current app... | What is the actual physical actuated quantity when controlling the position of a servo? |
<p>The Rock framework has such a widget (based on OpenPilot/GCS).</p>
<p>package</p>
<p><a href="http://rock-robotics.org/master/pkg/gui/map2d/index.html" rel="nofollow">http://rock-robotics.org/master/pkg/gui/map2d/index.html</a></p>
<p>code</p>
<p><a href="http://gitorious.org/rock-gui/map2d" rel="nofollow">http:... | 1036 | 2013-03-10T07:07:13.193 | |gps|visualization| | <p>Is there web mapping tool that allows developers to use it to plot GPS data of autonomous vehicles/robots?</p>
<p><code>Google Maps</code> forbids it. See <a href="https://developers.google.com/maps/terms">10.2.C</a>. <code>Google Earth</code> terms of use link jumps to the same page. <code>Bing</code> Maps looks t... | Web mapping that can be used for autonomous vehicles/robots |
<p>The Solid nodes (including Robot and Supervisor nodes) have a DEF name, like any other node and it is usually written in upper-case. These nodes also have a field "name". Both may be used by a Supervisor, it depends on which function is called. </p>
<p>In my case, the function getFromDef() expects a DEF name as arg... | 1039 | 2013-03-11T00:45:09.677 | |mobile-robot|simulator|webots| | <p>I am writing a method (Java) that will reset the position of e-puck in Webots. I have been following tutorial on <a href="https://cyberbotics.com/doc/guide/tutorial-8-the-supervisor" rel="nofollow noreferrer">Supervisor approach</a>. I have two controllers in my project:</p>
<ul>
<li>SupervisorController extends <a ... | Resetting position of e-puck in Webots using Supervisor node - problem with getting a handle to the robot |
<p>I'm biased (since I have TA'd his course twice), but I think Prof. Marin Kobilarov's derivation of the KF/EKF is far superior to Thrun's. I have read almost every book on KF/EKFs mentioned in previous answers, and I think Marin's lecture notes are excellent for the theoretical aspects of optimal state estimation. Th... | 1047 | 2013-03-12T07:59:49.377 | |kalman-filter|books| | <p>Currently I am reading a book of Mr. Thrun: <a href="http://www.probabilistic-robotics.org/" rel="noreferrer">Probabilistic Robotics</a>. I find it really helpfull to understand concept of filters, however I would like to see some code in eg. Matlab. Is the book "Kalman Filter for Beginners: with MATLAB Examples" wo... | Source to learn Kalman Fusion, explanatory code snippets |
<p>Yes, it is possible. You need the Android Accessory API and <a href="http://developer.android.com/tools/adk/index.html" rel="nofollow">Android Accessory Development Kit</a>. It is based off Arduino, and is open. </p>
<p>In general, if the phone + the ADK is cheaper than buying the components separately (I suspect i... | 1049 | 2013-03-12T16:25:48.563 | |arduino|usb| | <p>I want to built a robot and i need bunch of modules to track it like GSM/GPS Wifi and Camera
If i try to buy each of module separately it will cost me 300 dollar each aprox in Pakistan. On the other hand an android enable phone can be purchased on just 250$ having all of them. I was wondring if it is possible to int... | Is it possible to interface android mobile as GSM and GPS module with arduino based robotic applications? |
<p>That is a very good question, and depends on the design. There are in general two ranges for components which are temperature sensitive. The operational range gives the temperature at which the component can be actively used. Within the survival range the component should generally take no harm but may not be active... | 1050 | 2013-03-12T17:18:03.467 | |electronics|ugv|reliability| | <p>For example, if a rover has working temperature range of -70 to +120 Celsius, how does it survive and then restore itself if the temperature drops to -150 degrees for several months?</p>
| How do space rovers survive at very low temperatures? |
<p>Tripod gait is a stable gait. Moreover, it is a statically stable gait, meaning that if you lock the joints with 3 legs down and turn the power off, the robot will not topple. This implies that you don't need to dynamically balance the robot while walking. </p>
<p>The reason when a legged robot falls down is that i... | 1056 | 2013-03-13T10:09:37.960 | |motor|wheeled-robot|gait| | <p>I need help with figuring out the following things:</p>
<p>I'm developing a hexapod R-Hex type model with a tripod gait. However, the angles obtained during the robot's walking in real life are not perfectly aligned. Because of this the robot often collapses and falls even on perfectly straight terrain.</p>
<p>My ... | Perfecting Tripod Gait - Building a R-Hex Robot |
<blockquote>
<p>"I'm going to need analogue control"</p>
</blockquote>
<p>This is almost always done by rapidly connecting and disconnecting the motor to power, using PWM or something similar.
The switching is faster than the motor can respond, and often the designer picks a switching frequency faster than the 20 kH... | 1064 | 2013-03-14T11:18:41.797 | |arduino|motor| | <p>I want to prototype a therapeutic device that will have a lot of tiny mobile-phone type vibration motors <a href="http://www.cutedigi.com/robotics/vibration-motor.html" rel="nofollow">like this one</a> in it, and I want to be able to activate them in any configuration I want. I'm going to need analogue control, and... | Prototyping a device with 25-100 small DC 3.0V motors, is Arduino a good fit? |
<p>I have seen this behaviour using the NxtMMX with the EV3 (while writing the driver for ev3dev). I am fairly certain that this is the speed regulation PID overshooting and then slowing down. In NXC you can use <code>MMX_SetPerformanceParameters</code> to change the PID parameters and possibly get rid of the overshoot... | 1068 | 2013-03-15T01:42:18.520 | |nxt|mindstorms|not-exactly-c| | <p>I am trying to run a nxt motor using the mindsensors motor multiplexer at a slow speed. When I turn it on, it tends to jump approx 20 to 40 degrees before moving at a slow speed. Has anyone seen this behavior?</p>
<p>I am using NXT 1.0 with firmware down loaded from <code>lms_arm_mindsensors_129.rfw</code>. Samp... | Mindsensor Motor Multiplexer jump on run_unlimited |
<p>The gear trains in many printers and multifunction devices, and in some scanners, have a transfer gear that drives two different gears, depending on which way the drive motor is running. The pictures below show several such transfer gears in the left-side gear train of a Brother MFC-1970MC (<a href="http://reviews.... | 1069 | 2013-03-15T13:23:35.370 | |motor| | <p>Is there a way to use a single dc motor output for two different loads (by using gears, relays etc) ? Please see the illustration below:</p>
<p><img src="https://i.stack.imgur.com/obCuf.png" alt=""></p>
<p>To clarify the illustration, I get the dc motor power at "output 1" gear which is extended over an idler gear... | Is there a way to use a single dc motor output for two different loads? |
<p>The ring should be below the propeller. It is designed to keep the three screws in place in case some of the screws come out during the flight.</p>
| 1074 | 2013-03-16T12:37:15.563 | |brushless-motor| | <p>I'm building a quadcopter and I've received my motors and propellers.</p>
<p>What's the right way to assemble those together?</p>
<p>I'm not confident with what I've done, as I'm not sure the propeller would stay in place on a clockwise rotating motor.</p>
<p>I mean, if the motor rotates clockwise, will the screw... | How to assemble brushless motors and propellers? |
<p>I like @kramer65's answer but because you indicated you might like to make an encoder, I thought I'd share some information on that.</p>
<p><a href="http://www.societyofrobots.com/sensors_encoder.shtml" rel="nofollow noreferrer">http://www.societyofrobots.com/sensors_encoder.shtml</a> shows a very common way of mak... | 1078 | 2013-03-17T17:38:49.310 | |wheel|usb|encoding| | <p>For a pet project, I am trying to fly a kite using my computer. I need to measure how far a cord extends from a device. I also need to somehow read out the results on my computer. So I need to connect this to my pc, preferably using something standard like USB.</p>
<p>Since the budget is very small, it would be b... | How do I measure the distance that a cord (string) has moved? |
<p>This sounds like a classic case for a <a href="http://en.wikipedia.org/wiki/PID_controller">PID controller</a>. The "derivative" part of this controller will help prevent the arm from oscillating as you move to a new angle, and the "integral" part will help counteract the force of gravity acting on the arm.</p>
| 1082 | 2013-03-18T01:08:24.437 | |mobile-robot|control|robotic-arm| | <p>I have a 4-bar linkage arm (or similar design) for a telerobot used in the <a href="http://vexrobotics.com" rel="nofollow noreferrer">VEX Robotics Competition</a>. I want to be able to press buttons on my PS3-style controller to have the arm raise to certain angles. I have a potentiometer to measure the 4-bar's an... | Stabilizing a Robot Arm at a Specified Height |
<p>It is possible to do it. Take a look at this <a href="http://www.acroname.com/robotics/info/ideas/continuous/continuous.html" rel="nofollow">link</a>.
Of course you will not have the encoder possibility with that servo. But you dont have it currently either. You have to solder middle pin from rotary encoder (resisto... | 1086 | 2013-03-19T08:15:53.780 | |motor|rcservo| | <p>How do I increase the rotation range of a standard servo? Most servos have a rotation range of ~ 180 degrees. I would like to access the entire 360 degree range on the servo, partially because I would be attaching the servo's shaft to the robotic wheel and would like it to be able to make full rotations. Or is that ... | Increasing the rotation range of a servo motor |
<p><a href="http://docs.opencv.org/modules/refman.html" rel="nofollow">OpenCV</a> is available with python bindings. It's not geared at strictly numerical applications, but it might be sufficient. </p>
<p>It includes some <a href="http://docs.opencv.org/modules/core/doc/operations_on_arrays.html" rel="nofollow">matrix... | 1092 | 2013-03-19T21:26:07.550 | |kinematics|python| | <p>Are there any decent python numerical package libraries besides numpy for python? Numpy relies on gfortan which itself must be compiled correctly for your platform to avoid hidden/insidious numerical errors in numpy. </p>
<p>I need a matrix algebra package to do kinematics, path planning, and machine learning in py... | Numpy alternatives for linear algebra and kinematics in python? |
<p>The KF estimates the robot pose based on all sensor inputs <em>and the sensor correlation</em>. If you do an EKF on the compass data, you'd really need the robot pose to determine how likely a given compass reading <em>is</em>. Without that, you are
just low-pass filtering (not using a probabilistic filter like the... | 1097 | 2013-03-22T01:46:47.187 | |kalman-filter|imu| | <p>Shall I filter (kalman/lowpass) after getting the raw values from a sensor or after converting the raw values to a usable data? Does it matter? If so, why? </p>
<p>Example:
Filter after getting raw values from IMU
or
filter after converting raw values to a usable data eg. flight dynamics parameters.</p>
| At which stage should filtering be applied to the sensors data? |
<p>The definition of <code>robot</code> is as follows: </p>
<p><em>"A machine built to carry out some complex task or group of tasks, especially one which can be programmed"</em><br>
<a href="http://en.wiktionary.org/wiki/robot" rel="nofollow">wiktionary</a></p>
<p>So a robot is a tool which can be programmed. The K... | 1100 | 2013-03-22T02:46:07.920 | |industrial-robot| | <p>The definition of a robot is as follow: "A robotic paradigm can be described by the relationship between the three primitives of robotics: Sense, Plan, and Act."</p>
<p>An example could be the famous "Kuka Robots". The Kuka robot is preprogrammed and does mainly one loop over and over again. Some of them could have... | Why are industrial machines called robots? |
<p>A very effective and elegant approach is the resort to the so-called <strong>Potential Fields</strong>.</p>
<p>Essentially, each robot of the swarm generates a repulsive potential field which is tuned to be limited in the space around it (pretty much as a charged particle), so as any specific target is responsible ... | 1110 | 2013-03-27T17:43:01.053 | |algorithm|movement| | <p>I am trying to implement a mechanism to make robots avoid being too close (Say in a distance less than <code>d</code>). I am not familiar with those systems and I have to implement a strategy to avoid robots being too close to each other. Could anyone recommend me some readings for such a problem or a set of keyword... | Robots minimum distance |
<p>The motor they listed apparently has 1.548 kg·cm of torque at 4.8 V.
(As Ian pointed out, on this website -- like too many <a href="http://robosapiensindia.com/robomart/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=238&category_id=42&option=com_virtuemart&Itemid=64&vmcchk... | 1113 | 2013-03-28T06:17:54.370 | |stepper-motor|torque| | <p>I was looking up the motor parameters for some stepper motor where they listed the torque of the motor at different current/voltage but the torque they listed was in kg/cm.</p>
<p>How is kg/cm even a remotely acceptable unit for torque?</p>
<p>How do I calculate the torque in Nm from kg/cm?</p>
<p>Clarity note: I... | Torque in kg/cm? |
<p><strong>How to obtain your point correspondences</strong></p>
<p>There are many ways to do it, which can basically be classified into two categories: feature-based and dense matching.</p>
<p>Feature-based methods include using corner detectors, SIFT/SURF/ORB descriptors and other similar feature detectors that pro... | 1117 | 2013-03-28T09:18:05.097 | |computer-vision|stereo-vision| | <p>I am currently reading into the topic of stereo vision, using the book of Hartley&Zimmerman alongside some papers, as I am trying to develop an algorithm capable of creating elevation maps from two images.</p>
<p>I am trying to come up with the basic steps for such an algorithm. This is what I think I have to d... | How to obtain stereo correspondences and what exactly is a disparity map? |
<p>I've created an AI, which solves given IQ tests. You may test it on <a href="http://iqsolver.eu" rel="nofollow">http://iqsolver.eu</a></p>
| 1120 | 2013-03-28T16:42:32.603 | |artificial-intelligence| | <p>And if so, what was the highest score so far?</p>
<p>Some news articles suggest only parts of tests were aced.</p>
<hr />
<p>Update since people censored this question and closed it. There was an AI that has taken an IQ test and scored similar to a 4 year old.</p>
<p><a href="http://phys.org/news/2015-10-ai-machine-... | Has a robot ever taken a complete IQ test? |
<p>The <a href="https://robotics.stackexchange.com/a/1109/478">accepted answer</a> to your previous question presents several ways of developing enough drive for the vibrating motor, in its section called “Converting PWM signals into something that can drive a motor”. </p>
<p>One of the most direct ways is using one ... | 1143 | 2013-04-02T00:22:47.170 | |motor|power|pwm| | <p>This is a follow-up to this question: <a href="https://robotics.stackexchange.com/questions/1064/prototyping-a-device-with-25-100-small-dc-3-0v-motors-is-arduino-a-good-fit">Prototyping a device with 25-100 small DC 3.0V motors, is Arduino a good fit?</a></p>
<p>I've decided based on the answer that sending the co... | How do I interface a TLC5947 with small motors? |
<p>There are all sorts of mechanisms for handling dry goods. If you want to do it on a small scale, look to industrial devices for inspiration, but consumer and retail devices for quick solutions. For example, there are quite a few cereal dispensers on on the market like <a href="http://www.zevro.com/smartspace-dry-foo... | 1145 | 2013-04-02T07:50:25.177 | |automatic| | <p>I'm trying to handle food grains like rice, wheat in an automated way (to cook simple dishes). For this I have to transfer grain from a larger container to a weighing scale. I know I can use solenoid valves for liquids but all solid handling valves seem to be too big (gate valves etc) and for larger applications. Is... | What would be the best way to handle food grains? |
<p>Rather than trying to limit the 'x' and 'y' velocities separately, you should be limiting the overall velocity and calculating the component velocities from that overall velocity. In other words, something like:</p>
<pre><code>dx = currentX - nextX
dy = currentY - nextY
rate = min (maxRate, maxRate / sqrt( dx^2 + d... | 1158 | 2013-04-03T18:42:03.497 | |design| | <p>Some vector math is involved here so prepare yourself.</p>
<p>I am developing a robotic arm that moves in two dimensions. It is a rotary-rotary design which looks roughly like the picture in this post:
<a href="https://robotics.stackexchange.com/questions/869/building-robotic-arm-joint">Building Robotic arm joint<... | Equation to limit rate of change of end-effector in X and Y coordinates |
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